1 //===--- UnusedAliasDeclsCheck.cpp - clang-tidy----------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "UnusedAliasDeclsCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang::tidy::misc {
17
registerMatchers(MatchFinder * Finder)18 void UnusedAliasDeclsCheck::registerMatchers(MatchFinder *Finder) {
19 // We cannot do anything about headers (yet), as the alias declarations
20 // used in one header could be used by some other translation unit.
21 Finder->addMatcher(namespaceAliasDecl(isExpansionInMainFile()).bind("alias"),
22 this);
23 Finder->addMatcher(nestedNameSpecifier().bind("nns"), this);
24 }
25
check(const MatchFinder::MatchResult & Result)26 void UnusedAliasDeclsCheck::check(const MatchFinder::MatchResult &Result) {
27 if (const auto *AliasDecl = Result.Nodes.getNodeAs<NamedDecl>("alias")) {
28 FoundDecls[AliasDecl] = CharSourceRange::getCharRange(
29 AliasDecl->getBeginLoc(),
30 Lexer::findLocationAfterToken(
31 AliasDecl->getEndLoc(), tok::semi, *Result.SourceManager,
32 getLangOpts(),
33 /*SkipTrailingWhitespaceAndNewLine=*/true));
34 return;
35 }
36
37 if (const auto *NestedName =
38 Result.Nodes.getNodeAs<NestedNameSpecifier>("nns")) {
39 if (const auto *AliasDecl = NestedName->getAsNamespaceAlias()) {
40 FoundDecls[AliasDecl] = CharSourceRange();
41 }
42 }
43 }
44
onEndOfTranslationUnit()45 void UnusedAliasDeclsCheck::onEndOfTranslationUnit() {
46 for (const auto &FoundDecl : FoundDecls) {
47 if (!FoundDecl.second.isValid())
48 continue;
49 diag(FoundDecl.first->getLocation(), "namespace alias decl %0 is unused")
50 << FoundDecl.first << FixItHint::CreateRemoval(FoundDecl.second);
51 }
52 }
53
54 } // namespace clang::tidy::misc
55